linux-kernel - Re: [PATCH] x86/crypto: Add missing RETs

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Message-ID: <20180625072438.GA19063@gmail.com>
Date:   Mon, 25 Jun 2018 09:24:38 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Alexey Dobriyan <adobriyan@...il.com>
Cc:     Borislav Petkov <bp@...en8.de>, linux-crypto@...r.kernel.org,
        Mike Galbraith <efault@....de>, torvalds@...ux-foundation.org,
        tglx@...utronix.de, jpoimboe@...hat.com, luto@...nel.org,
        peterz@...radead.org, brgerst@...il.com, hpa@...or.com,
        linux-kernel@...r.kernel.org, dvlasenk@...hat.com,
        h.peter.anvin@...el.com,
        linux-tip-commits <linux-tip-commits@...r.kernel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH] x86/crypto: Add missing RETs


* Alexey Dobriyan <adobriyan@...il.com> wrote:

> On Sun, Jun 24, 2018 at 09:11:05AM +0200, Ingo Molnar wrote:
> > > Add explicit RETs to the tail calls of AEGIS and MORUS crypto algorithms
> > > otherwise they run into INT3 padding due to
> > > 
> > >   51bad67ffbce ("x86/asm: Pad assembly functions with INT3 instructions")
> > > 
> > > leading to spurious debug exceptions.
> > > 
> > > Mike Galbraith <efault@....de> took care of all the remaining callsites.
> > 
> > Note that 51bad67ffbce has been zapped because it caused too many problems like 
> > this, but the explicit RETs make sense nevertheless.
> 
> So commit which found real bug(s) was zapped.
> 
> OK

No, what happened is that the commit was first moved into WIP.x86/debug showing 
its work-in-progress status, because it was incomplete and caused bugs:

   https://lore.kernel.org/lkml/20180518073644.GA8593@gmail.com/T/#u

... and finally, after weeks of inaction I zapped it because I didn't see progress 
and you didn't answer my question.

If a fixed patch with updated tooling to detect these crashes before they occur on 
live systems is submitted we'll reconsider - it didn't get NAK-ed, it's just 
incomplete in the current form.

Thanks,

	Ingo